The present invention relates to crosslinkable particles, a resin composition comprising the crosslinkable particles and a cured product made from the resin composition. More particularly, the present invention relates to crosslinkable particles exhibiting superior dispersion stability and storage stability without producing any depositions or precipitates, and without increasing the viscosity or producing gels during storage; a resin composition comprising crosslinkable particles, which is capable of forming coatings with high hardness, superior scratch resistance, low curling properties, superb adhesion, and excellent transparency, and fine appearance on the surface of various substrates for example plastics (polycarbonate, polymethylene acrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS resin, AS resin, norbornene resin, etc.), metals, woods, papers, glass and slates. These substrates may be either in the shape of a film or a formed three-dimensional object. The resin composition and the cured product are suitable for use as, for example, a protective coating material to prevent stains or scratches on plastic optical parts, touch panels, film-type liquid crystal elements, plastic containers, or flooring materials, wall materials, and artificial marbles which are used for architectural interior finish; an adhesive and a sealing material forvarious substrates; and a vehicle for printing ink.
In recent years, a resin composition exhibiting excellent curability, superior storage stability, coatability and capability of forming coatings with high hardness, superior scratch resistance, low curling properties, superb adhesion, excellent transparency, and superior coating appearance has been desired as a protective coating material to prevent stains or scratches on the surface of various substrates, an adhesive and a sealing material for various substrates, or a vehicle for printing ink. Various materials in which colloidal silica is incorporated have been proposed with an objective to improve the scratch resistance among these required characteristics. For example, U.S. Pat. Nos. 3,451,838 and 2,404,357 disclose compositions comprising a hydrolyzate of alkoxysilane and colloidal silica as major components to be used as a heat-curable coating material. Japanese Patent Publication No. 21815/1987 discloses a composition for a photocurable coating material comprising an acrylate and particles of colloidal silica of which the surface is modified by methacryloxysilane. A feature of these coating materials is to improve performance of the coating materials by treating the surface of silica particles with a specific organic silane or under specific conditions. However, these coating materials do not satisfy all the requirements such as curability, storage stability and coatability as a resin, and high hardness, superior scratch resistance, low curling properties, superb adhesion, excellent transparency, and coating appearance when made into coatings.
Furthermore, Japanese Patent Application Laid-open No. 100111/1997 discloses reactive silica particles produced by bonding silica particles and an organic compound having a polymerizable unsaturated group through a silyloxy group.
However, these reactive silica particles produce deposits or precipitates when used in the form of a sol in which the particles are dispersed in a solvent, and thus do not necessarily exhibit satisfactory dispersion stability.
Although the resin composition comprising these crosslinkable particles is excellent in curability and produces cured coatings with superior hardness, scratch resistance, low curling properties, and adhesion properties, and the like, the following properties are not necessarily satisfied.
Specifically, the resin composition does not always exhibit sufficient storage stability in that the composition may produce precipitates and its viscosity may increase with time. Particularly, the tendency is conspicuous with the increase of the particle concentration. In addition, the appearance of coatings may be poor that is, the coated surface may not be smooth, may have striations, be repellent and whitened, or have an orange-peel appearance. Moreover, the coating films may be have poor transparency and produce haze.
Particularly, because of an increase of the productivity in the manufacture of coated products in recent years, there has been improvement in production facilities such as an increase of the product line speed and an increase of a dryer air speed and drying temperature. Such improvement in production facilities, however, causes an impaired appearance of coatings such as production of a wavy striation, streaks, unevenness of coatings, and cissing.
The present invention has been completed in view of the above-described problems and has an object of providing a resin composition exhibiting excellent curability, coatability and capability of forming coatings with high hardness, superior scratch resistance, low curling properties, superb adhesion, excellent transparency, and superior coating surface appearance without a wavy striation, streaks, unevenness of coatings, cissing, and the like, as well as cured products or composite materials produced by applying and curing the resin composition on the surface of a substrate. A further objective is providing crosslinkable particles exhibiting superior dispersion stability and storage stability without producing any depositions or precipitates, and without increasing the viscosity or generating gels during storage.
As a result of extensive studies, the present inventors have found that the products satisfying all the above characteristics can be obtained by a resin composition comprising (A1) crosslinkable particles (A) prepared by bonding oxide particles (A1) of a specific element and a specific organic compound (A2) having a specific group, (B) a compound which possesses 4 or more polymerizable unsaturated groups in the molecule, and (C) a compound which possesses one (1) to three (3) polymerizable unsaturated groups in the molecule.